Machine and method for controlling textile fabric defects during the textile production and method for retrofitting a circular knitting machine having a fixed support structure, a rotational support structure, said system comprising: a digital camera for capturing digital images of the knitted textile fabric, a data processor for processing the captured digital images, a camera support structure for holding the camera, a lighting system to illuminate the knitted textile fabric from the camera side for capture by the digital camera; wherein the camera and back support structures are fixed to the rotational structure.